Fuel filter assembly

ABSTRACT

A fuel filter is provided which comprises a manifold, a connector element, a filter bowl, a filter element, an inlet shutoff valve, an outlet shutoff valve, an inlet port, an inlet passage, an outlet port, an outlet passage and a relief valve in which the connector element is fixed to the manifold, and the filter bowl is reversibly fixed to the connector element. The filter bowl is adapted to reversibly receive the filter element and is so configured that when the filter element is located within the filter bowl and the filter bowl attached to the connection element the filter element divides the space defined by the connector element and filter bowl into an inlet filter chamber and an outlet filter chamber. The inlet port mouths through a surface of the manifold, and the inlet port and inlet filter chamber are in fluid communication via the inlet passage.

FOREIGN PRIORITY

This application claims priority to Polish Application No. P.433387filed Mar. 30, 2020, the entire contents of which is incorporated hereinby reference.

TECHNICAL FIELD

This disclosure relates to fuel filters and in particular to fuelfilters having a filter bypass valve and shutoff valves on the fuelinlet and outlets.

BACKGROUND

Known fuel filters comprise a filter bowl suitable for housing a filterelement, a filter element, and a manifold to which the filter bowl maybe reversibly attached. The manifold includes fuel inlet and outletports. In combination the manifold, filter bowl and the filter elementdefine a flow path in which fuel flows into the manifold through thefuel inlet port, through the filter element and out of the manifold viathe fuel outlet port.

SUMMARY

According to an aspect of this disclosure there is provided a fuelfilter comprising a manifold, a connector element, a filter bowl, afilter element, an inlet shutoff valve, an outlet shutoff valve, aninlet port, an inlet passage, an outlet port, an outlet passage and arelief valve in which the connector element is fixed to the manifold,and the filter bowl is reversibly fixed to the connector element, thefilter bowl is adapted to reversibly receive the filter element and isso configured that when the filter element is located within the filterbowl and the filter bowl attached to the connection element the filterelement divides the space defined by the connector element and filterbowl into an inlet filter chamber and an outlet filter chamber, theinlet port is incorporated in the manifold, and the inlet port and inletfilter chamber are in fluid communication via the inlet passage, theoutlet port is incorporated in the manifold and the outlet port andoutlet filter chamber are in fluid communication via the outlet passage,the inlet shutoff valve is biased by a biasing means into a closedconfiguration which prevents fuel flowing along the inlet passage whenthe filter bowl is not connected to the connector element, connection ofthe filter bowl to the connector element causes the inlet shutoff valveto be impelled into an open configuration which allows fuel to flowalong the inlet passage, the outlet shutoff valve is biased by a biasingmeans into a closed configuration which prevents fuel flowing along theoutlet passage when the filter bowl is not connected to the connectionelement, connection of the filter bowl to the connection element causesthe outlet shutoff valve to be impelled into an open configuration whichallows fuel to flow along the outlet passage, the relief valve is biasedby a biasing means into a closed configuration in which fuel flowingbetween the inlet passage and outlet passage passes through the filterelement, and movement of the relief valve into an open configurationallows fuel to flow between the inlet passage and the outlet passage viathe relief valve without the fuel passing through the filter element,and the relief valve is caused to move into its open configuration whena predetermined fuel pressure is reached within the inlet passage andinlet chamber.

In some embodiments, the impelling of the inlet shutoff valve and theoutlet shutoff valve into their open configuration commences aftercommencement of connection of the fuel filter bowl to the connectorelement and before the fuel filter bowl is fully connected to theconnector element. That is the movement of the inlet and outlet shutoffvalves toward their open configurations, and thus the partial opening ofthose valves, only commences once the connection of the fuel filter bowlto the connector element has begun. This ensures that any fuel releasedby the valves when they begin to open is caught in the fuel filter bowland there is no risk of spillage.

For the purposes of the present disclosure, reference to “fullyconnected” when referencing the connection of the filter bowl to theconnector element is to be understood to mean for connections such asscrew threaded connections that the filter bowl is screwed to theconnector element to the maximum extent possible.

An advantage of the fuel filter of the disclosure is that when thefilter bowl is not attached to the connector element the inlet andoutlet shutoff valves are both in their closed configurations with theresult that fuel does not leak out of the connector element, manifold orfuel lines leading to and from the fuel inlet and fuel outlet portsrespectively. This means that when servicing the fuel filter, forexample changing the filter element, the fuel lines do not need to bedetached from the manifold. It is further the case that when the filterbowl is being detached from the connector means the biasing means willcause the inlet and outlet shutoff valves to automatically move intotheir closed configurations. As such, the removal of the filter bowl isexpected to leave the person removing the filter bowl with some fuel inthe filter bowl which can then be safely stored or disposed of but therewill be no fuel leaking from the manifold or connector element. Theseadvantages have the result that servicing the fuel filter can be simpleand swift and as such the costs associated with such a servicing can beminimised.

A further advantage of the fuel filter of the disclosure is that theconnector element can be adapted to be attached to existing knownconfigurations of fuel filter manifolds. This has the result that a fuelfilter of the current disclosure can be fitted to an existing mechanismwhich incorporates a fuel filter, for example a gas turbine engine forus in an aircraft, without having to change the manifold.

A further advantage of the disclosure is that mechanically the fuelfilter of the disclosure is relatively simple and can be made to acompact design. This can lead to a high degree of reliability and againreduced maintenance costs.

The filter bowl is configured to have the form of a bowl with an openmouth. In some embodiments of the above embodiments of the currentdisclosure the filter bowl is connected to the connector element via ascrew thread adjacent to the open mouth of the filter bowl and acorresponding thread on the connector element. In some other embodimentsthe filter bowl is connected to the connector element via othermechanical engagement means where the act of connection of the filterbowl to the connector element means causes the filter bowl generally,and the base of the filter bowl specifically, to move closer to theconnector element as connection occurs.

In some embodiments of the above embodiments the relief valve is causedto move into its open configuration when a predetermined fuel pressureis reached within the inlet passage and inlet chamber. This isadvantageous because in normal operating conditions a fuel pump willpump fuel into the fuel filter and the fuel pressure within the inletpassage and inlet chamber will, among other factors, be a function ofthe pumping, the pressure drop across the filter element, and therelated flow rate of fuel through the filter element. As the filterelement traps material in the material of the filter the pressure dropacross the filter element increases and the flow rate decreases untilthe filter element is sufficiently blocked that there is insufficientflow through the filter element. When the fuel within the inlet passageand inlet chamber reaches a predetermined pressure the pressure reliefvalve will be pushed open by the pressurised fuel. Fuel will then flowdirectly from the inlet passage or inlet chamber to the outlet chamberor outlet passage. This ensures that sufficient fuel exits the fuelfilter via the fuel outlet port for continued operation of the mechanismin which the fuel filter of this disclosure is incorporated. Fuel willcontinue to flow through the relief valve until the fuel pressure withinthe inlet passage and inlet chamber drops below the predeterminedpressure at which time the relief valve will revert to its closedconfiguration.

The maximum rate of flow of fuel through the fuel filter can bepredetermined by designing the filter element and filter bowl to allow amaximum predetermined rate of fuel flow to occur. A non-limiting exampleof such a maximum desired fuel flow is 20 000 pph (2.520 Kg/s).

In some embodiments of the above embodiments of the current disclosurethe inlet passage comprises a second inlet chamber in which one or bothof the manifold and the connection means define the second inlet chamberand first and second inlet chamber apertures, in which the first inletchamber aperture is a mouth of the portion of the inlet passageextending from the fuel inlet port, and at least one sliding seal meansextends around the edge or inner face of the second inlet chamberaperture, the inlet shutoff valve comprises a longitudinally extendingconduit element, the conduit element is configured to extend through thesecond inlet chamber aperture in a sliding engagement with the slidingseal means, the conduit element comprises a first closed end, a secondend, one or more side walls, and a stop means, the one or more sidewalls of the conduit element extend between the first and second ends,at least one side wall of the conduit element defines at least one firstfuel aperture passing through the side wall at a position spaced fromthe first end, the stop element of the conduit element extends laterallyfrom the first end or from one or more side walls adjacent the firstend, the stop element of the conduit element prevents the first end ofthe conduit element passing through the second inlet chamber aperture,each first fuel aperture of the conduit element is sufficientlylongitudinally spaced from the first end of the conduit element thatwhen the stop element abuts the face of the manifold or connection meansthat defines the second inlet chamber aperture each sliding seal meansis in contact with a blank portion of the or each side wall, the blankportion of the or each side wall of the conduit element contains nofirst fuel apertures and lies longitudinally between the first end andthe or each fuel aperture, the conduit element further comprises one ormore second fuel apertures which are defined by one or more of the sidewalls of the conduit element, the one or more second fuel apertures ofthe conduit element are located longitudinally between the one or morefirst fuel apertures and the second end of the conduit, and the conduitelement is dimensioned and configured so that when the filter bowl isfully attached to the connector element the second end of the conduitelement abuts a part of the filter bowl, the first fuel apertures mouthinto the second inlet chamber and the second fuel apertures mouth intothe inlet filter chamber.

In this embodiment the conduit element acts as part of the inlet passageand movement of the conduit element between the configuration where thefirst fuel apertures mouth into the first inlet chamber (the openconfiguration of the inlet shutoff valve) and the configuration wherethe first fuel apertures are out of fluid communication with the firstinlet chamber because the sliding seal means is between the aperturemouths and the first inlet chamber (the closed configuration of theinlet shutoff valve). The second end of the conduit element forms partof the inlet passage and may, in some embodiments, be located in theinlet filter chamber. The second end of the conduit element can be open,or the conduit element may be of other configurations that allow fuelthat enters the conduit element via the first fuel apertures to exit theconduit element.

The advantage of this embodiment is that any fuel in the conduit elementwhen the filter bowl is removed from the connector element may beexpected to drain into the filter bowl. A further advantage of thisembodiment is that the second inlet chamber may be of sufficientdimensions (in a direction substantially perpendicular to thelongitudinal axis of the conduit element) that there is an unrestricted,non-turbulent, flow of the fuel through the second inlet chamber andinto the first fuel apertures.

In some embodiments of the above embodiments of the current disclosurethe conduit element further comprises one or more second fuel apertureswhich are defined by one or more of the side walls of the conduitelement, the one or more second fuel apertures are located between theone or more first fuel apertures and the second end of the conduitelement, and the conduit element is dimensioned and configured so thatwhen the filter bowl is fully attached to the connector element thesecond end of the conduit element abuts a part of the filter bowl, thefirst fuel apertures of the conduit element mouth into the second inletchamber and the second fuel apertures of the conduit element mouth intothe inlet filter chamber.

In these embodiments the second fuel apertures are longitudinally spacedfrom the first fuel apertures and separated by a blank portion of theconduit element. Again this blank portion includes no apertures throughthe side wall or walls of the conduit element.

In some embodiments where the filter bowl is screwed onto the connectorelement, the second end of the conduit element connects with the portionof the filter bowl at or adjacent to the intersection of the filter bowland the axis of the thread on the filter bowl that engages with theconnector element.

An advantage of these embodiments is that the conduit element can be sodimensioned that the filter bowl does not make contact with the conduitelement until the filter bowl is at least partially attached to theconnector element. This avoids the inlet shutoff valve being opened tooearly leading to accidental spillage of fuel as the filter bowl isattached to the connector element.

In some embodiments of the above embodiment of the current disclosurethe fuel filter further comprises an intermediate structure, in whichthe second end of the conduit element abuts a part of the filter bowlvia the intermediate structure when the filter bowl is fully attached tothe connector element, and the intermediate structure is configured anddimensioned so that the biasing means may displace the intermediatestructures and move the conduit element into the closed configurationwhen the filter bowl is detached from the connection element.

In some other embodiments of the above embodiment of the currentdisclosure the fuel filter further comprises an intermediate structure,in which the second end of the conduit element abuts a part of thefilter bowl via the intermediate structure when the filter bowl is fullyattached to the connector element, and the intermediate structure isintegral to or attached to the filter bowl.

In either of the above embodiments with an intermediate structure, theintermediate structure may also be so dimensioned, located andconfigured that it serves to locate and or retain the filter element inthe filter bowl. The intermediate structure may be in sliding fit with aportion of the filter element so as to retain the filter element in thefilter bowl.

In some embodiments of the above embodiments of the current disclosurethe biasing means directly or indirectly biases the conduit element intothe inlet shutoff valve closed configuration by biasing the stop meansinto a position where it prevents movement of the first end of theconduit element in the direction of the second end of the conduitelement.

In some embodiments of the above embodiments of the current disclosurethe outlet passage comprises a second outlet chamber, and one or moreoutlet intermediate structures in which one or both of the manifold andthe connection means defines the second outlet chamber and a first andone or more second outlet chamber apertures, the first outlet chamberaperture is a mouth of the portion of the outlet passage extending fromthe fuel outlet port, each second outlet chamber aperture is in fluidcommunication with the outlet filter chamber, the outlet shutoff valvecomprises an aperture closure element, the aperture closure element isconfigured to overlie all of the second outlet chamber apertures, theaperture closure element is movable between a closed configuration inwhich the aperture closure element closes all of the second outletchamber apertures and an open configuration spaced from the secondoutlet chamber apertures, the aperture closure element is biased intothe closed configuration by the biasing means, and each outletintermediate structure is dimensioned and configured to contact aportion of the filter bowl when the filter bowl is fully attached to theconnector element, the outlet intermediate structures impel the apertureclosure element into its open configuration when the filter bowl isattached to the connector element, and the outlet intermediatestructures allow the biasing means to displace those structures and movethe aperture closure element into the closed configuration when thefilter bowl is detached from the connection element.

A number of second outlet chamber apertures may be included in the fuelfilter of the present disclosure so that there is no restriction on theflow of fuel out of the outlet filter chamber through the second chamberapertures.

In some embodiments of the above embodiments of the current disclosurethe fuel filter comprises one or more outlet intermediate structures inwhich the or each outlet intermediate structures are dimensioned andconfigured to contact a portion of the filter bowl at least when thefilter bowl is fully attached to the connector element, the outletintermediate structures impel the aperture closure means into its openconfiguration when the filter bowl is fully attached to the connectorelement, and the one or more outlet intermediate structures allow thebiasing means to displace the one or more outlet intermediate structuresand move the aperture closure means into the closed configuration whenthe filter bowl is detached from the connection element.

An advantage of this embodiment of the present disclosure is that eachsecond outlet chamber aperture is automatically closed as the filterbowl is moved away from the connector element.

An advantage of this embodiment is that the or each outlet intermediatestructure can be so dimensioned that the filter bowl does not makecontact with those structures until the filter bowl is at leastpartially attached to the connector element. This again avoids anyaccidental spillage of fuel as the filter bowl is attached to theconnector element.

In some embodiments of the above embodiment of the current disclosurethe or one of the outlet intermediate structures is the conduit elementof the inlet shutoff valve. This has the advantage that the number ofcomponents in the fuel filter is minimised which leads to weight andcost savings. Further, such an arrangement also ensures that the inletand outlet shutoff valves are opened and closed at substantially thesame time as each other.

In some embodiments of the above embodiments of the current disclosureat least one of the first and biasing means is a compression spring.

In some embodiments of the above embodiments of the current disclosurethe biasing means associated with the inlet and outlet shutoff valvesare the same biasing means. This again has the advantage that the numberof components in the filter is minimised which leads to weight and costsavings.

In some embodiments of the above embodiments of the current disclosurethe relief valve comprises a means for adjusting the force with whichthe biasing means biases the relief valve into its closed configuration.This has the advantage that the relief valve may be calibrated to openat a specific predetermined fuel pressure in the filter inlet chamberand inlet filter passage. In some embodiments, the adjustment may beperformed by the insertion or removal of shims between one end of thebiasing means and whatever structure that end of the biasing means isbearing against.

In some embodiments of the above embodiments of the current disclosurethe relief valve comprises a valve seat and a valve plug, the biasingmeans biases the valve plug against the valve seat (the closedconfiguration of the relief valve), and the valve plug may be impelledto move to a position spaced from the valve seat (the open configurationof the relief valve).

In some embodiments of the above embodiments of the current disclosurethe valve plug has a frustoconical configuration and the valve seat isconfigured accordingly.

In some embodiments of the above embodiments of the current disclosurethe valve seat defines at least part of a passage between the inletfilter chamber and the outlet filter chamber where the relief valve isdownstream of the inlet shutoff valve and upstream of the outlet shutoffvalve.

In this description references to upstream and downstream are withreference to the flow of fuel through the fuel filter from the fuelfilter inlet port through the inlet passage, into the filter inletchamber, through the filter element into the filter outlet chamber, andthrough the outlet passage to the outlet port.

In some embodiments of the above embodiments of the current disclosurethe valve plug of the relief valve defines a plug aperture extendingthrough the plug, the plug aperture has an orientation substantiallyparallel to the direction of movement of the valve plug between the openand closed configurations of the relief valve, the conduit element ofthe inlet shutoff valve passes through the plug aperture with a portionof the or each side wall of the conduit element between the first andsecond fuel apertures of the conduit element in a sliding sealingengagement with the valve plug. The sliding sealing engagement may beachieved using one or more sliding seal means each of which are retainedin or adjacent to the plug aperture.

In some embodiments of the above embodiments of the current disclosurethe conduit element of the inlet shutoff valve comprises a biasing meansmounting element, and the biasing means extends between and bears uponthe valve plug of the relief valve and the biasing means mounting of theconduit element. An advantage of this arrangement is again that that thenumber of components in the filter is minimised which leads to weightand cost savings.

In some embodiments of the above embodiment of the current disclosurethe biasing means associated with the relief valve exerts less biasingforce than the biasing means associated with the conduit element. Anadvantage of this arrangement is that the lower biasing force of thebiasing means associated with the relief valve relative to the biasingmeans associated with the conduit element ensures that when the filterbowl is disconnected from the connector element the biasing means doesnot prevent the closure of the inlet shutoff valve.

In some embodiments of the above embodiments the relief valve of thefuel filter of the present disclosure is formed from stainless steel4403, the or each biasing means from spring steel, the or each sealelement from a suitable fluorocarbon, and the remaining parts fromaluminium 6061 or aluminium T651. In other embodiments, other suitablematerials may be used to form the parts of the fuel filter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described and explained by way ofexample with reference to the accompanying drawings in which

FIG. 1 shows a perspective view of an embodiment of a fuel filter of thepresent disclosure;

FIG. 2 shows a first side view of the fuel filter of FIG. 1;

FIG. 3 shows a second side view of the fuel filter of FIG. 1;

FIG. 4 shows a section A-A of the fuel filter of FIG. 2;

FIG. 5 shows a section B-B of the fuel filter of FIG. 3;

FIG. 6 shows an exploded view of the components of the fuel filter ofFIG. 1;

FIG. 7 shows an enlarged view of the conduit element of the fuel filterof FIG. 1; and

FIGS. 8a and 8b show a schematic view of the outlet shutoff valve inopen and closed configurations.

DETAILED DESCRIPTION

With reference to FIGS. 1, 2 and 3, a fuel filter 2 is comprised of amanifold 4, to which is attach a connector element 6. Reversiblyconnected to the connector element 6 is a filter bowl 8.

The manifold 4 defines a fuel inlet port 10 and a fuel outlet port 12.The fuel inlet and outlet ports 10, 12 are provided with means (notshown) to engage with the ends of a fuel input line (not shown) and afuel output line (not shown) respectively.

With reference to FIGS. 4 and 5, to enhance the clarity of theseFigures, some elements described below and shown in these Figures arelabelled in only one of the Figures.

With reference to FIGS. 4, 5 and 6, the connector element 6 is attachedto the manifold 4 by a number of bolts 14 with an annular gasket 16between the abutting faces of the connector element 6 and manifold 4.

The filter bowl 8 is adapted to reversibly engage with the connectionmeans 6 via a helical screw thread (not shown) which is formed on theface of a portion of the radially outer face of the filter bowl element70 and the radially inner face of connector element portion 72. Thescrew thread is dimensioned so that filter bowl element 70 may bescrewed into the connector element portion 72 until the stop 76 on thefilter bowl 8 abuts the edge 80 of the connector element portion 72.When the stop 76 on the filter bowl abuts the edge 80 of the connectorelement portion 72 the portion of the filter bowl element 70 furthestfrom the filter bowl base 78 is adjacent to the annular seals 74 and afuel tight seal is formed between the connector element portion 72 andthe filter bowl element 70. The annular seals 74, are retained in a pairof annular grooves (not labelled) in the inner face of connector elementportion 72.

The annular seals 74 are o-rings and are formed of a fluorocarbon thatis suitable for high temperatures and which has good chemicalresistance, for example Viton (Registered trade mark) GLT which isavailable from DuPont Performance Elastomers. This is also the materialused in connection with other annular seals, in particular o rings, usedin this embodiment of a fuel filter according to the current embodimentof the present disclosure.

The filter bowl 8 is configured and dimensioned to substantiallysurround a known filter element 110. The filter element 110 iscylindrical and constructed to filter fuel that is flowing radiallyoutwardly from an inlet filter chamber 92 in the inside of the cylinderof the filter element 110 to an outlet filter chamber 64 outside thefilter element 110.

The base 78 of the filter bowl 8 is configured to engage with a firstend of the filter element 110. The engagement is a push fit of thefilter element 110 onto a spindle 114. The push fit is sufficientlytight that fuel will not flow through the joint between the filterelement and the spindle 114.

The manifold 4 defines an inlet passage 18 which extends from the fuelinlet port 10 to a second inlet chamber 20. The second inlet chamber isdefined in part by a recess face 22 in the manifold 4 and in part by achamber element 24 and wall 36 of the connector element 6. Recess face22, chamber element 24 and wall 36 define substantially cylindricalvolumes and chamber element 24 is configured to be a sliding fit withinthe recess face 22. An annular seal 28, such as an o ring, is retainedin an annular grove 26 in the radially outer surface of the chamberelement 24 to form a fuel tight seal between the chamber element 24 andrecess face 22.

The second inlet chamber 20 has a first inlet chamber aperture 30 and asecond inlet aperture 32. The first inlet chamber aperture 30 is themouth of the inlet passage 18 into the second inlet chamber 20 andpasses through recess face 22 of the manifold 4. The second inletaperture 32 is defined by the wall 36 of the connector element 6 and theface of wall 36 defining the aperture 32 includes an annular grove (notlabelled) in which is retained an annular seal 34, such as an o ring.

The second inlet aperture 32 is circular in cross section (in the planeof the wall 36 of the connector element 4) and is dimensioned so that acylindrical conduit element 38 with a side wall 40 can pass through theaperture 32 and the side wall 40 of the conduit element is in a slidingfit with the face of the wall 36 defining the aperture 32. The annularseal 34 forms a fuel tight seal between the face of wall 36 defining theaperture 32 and the side wall 40 of the conduit element when the sidewall 40 has a blank portion that is a portion of the side wall 40without apertures.

The conduit element 38 has a first closed end 42. Adjacent to the closedend 42 is an annular grove (unlabelled) in which a stop means 44 isretained.

Spaced from the longitudinal face of the stop means 44 furthest from theclosed end 40 of the conduit element 38 are a plurality of first fuelapertures 46. The portion 48 of the side wall 40 between the stop means44 and the first fuel apertures 46 is a blank portion of side wall thatis, in a longitudinal direction, at least as long as the thickness ofthe wall 36 of the connector element 6. When the stop means 44 is incontact with the wall 36 the sliding seal means 34 is in contact withthe portion 48 of the side wall 40 which seals the aperture 34 as awhole. As such, the conduit element 38 is, when the stop means 44 is incontact with the wall 36 of the contact element 6, the inlet shutoffvalve in its closed configuration.

The conduit element 38 is of a length such that the second end 82 of theconduit element 38 abuts and sits within a cup 84 at the centre of thebase 78 of the filter bowl 8. The abutment of second end 82 in the cup84 has the advantage that when the filter bowl 8 is being screwed ontoconnection element 6 the cup 84 prevents any risk of the rotation of thefilter bowl 8 causing the second end 82 of the conduit element 38 tomove away from the centre of the filter bowl base 78 and potentially jamthe conduit element 38 in a skewed position in aperture 32.

The conduit element is of such a length that when the second end 82 ofthe conduit element 38 is in the cup 84 sufficient of the conduitelement 38 adjacent its first end 42 projects through the aperture 32toward the manifold 4 that the first fuel apertures 46 entirely mouthinto the second inlet chamber 20 as shown in FIGS. 4 and 5 and is theinlet shutoff valve in its open configuration. This allows fuel to flowfrom the second inlet chamber 20 through the first fuel apertures 46 andinto the conduit 86 of the conduit element 38.

The side wall 40 of the conduit element 38 further defines a number ofsecond fuel apertures 88 at a longitudinal position separated from thefirst fuel apertures 46 by a blank portion of the wall 90. Thelongitudinal dimension of the blank portion of the wall 90 is sufficientthat some or all of the second fuel apertures 88 mouth into the filterinlet chamber 92 irrespective of the position of the conduit element 38as it sits at the inlet shutoff valve open or closed configuration or atsome position between those two configurations.

The manifold 4 and the connector element 6 define an annular secondoutlet chamber 50 between faces 52 and 54 of the manifold 4, theradially outer face of chamber element 24 and wall 56 of the connectorelement 6. The face 52 of the manifold 4 defines a first outlet chamberaperture 60 and the wall 56 of the connector element 6 defines a numberof second outlet chamber apertures 58.

The first outlet chamber aperture 60 is the mouth of the outlet passage62 which extends to the fuel outlet port 12. The second outlet chamberapertures 58 are in communication with the outlet filter chamber 64.

In a loose sliding fit with and extending around the chamber element 24of the connector element 6 is a plate element 66. The plate element 66is dimensioned so as to overlie all of the second outlet chamberapertures 58 when the plate element 66 is in contact with the wall 56 ofthe connector element 6. The face of the plate element 66 which contactsthe wall 56 is proved with a flexible seal coating (not labelled) withthe result that when the plate element 66 is impelled into contact withthe wall 56 a fuel tight seal is created between the plate element 66and the wall 56 and fuel cannot then pass through the second outletchamber apertures 58. A biasing means 68 in the form of a compressionhelical spring is compressed between the face 54 of the manifold 4 andthe plate element 66 and impels the plate element 66 into contact withthe wall 56. When the plate element 66 is impelled into contact with thewall 56 and the second outlet chamber apertures 58 are sealed the plateelement 66 is the outlet shutoff valve and is in the outlet shutoffvalve closed configuration.

As shown in FIGS. 7, 8 a and 8 b, the conduit element 38 furthercomprises a biasing means mounting element 94 in the form of a plate 96from which four pegs 98 (one of which is obscured in FIG. 7) areupstanding. The plate 96 extends radially outward from the side wall 40and is longitudinally positioned on the conduit element 38 between thefirst fuel apertures 46 and the second fuel apertures 88 at a positionwhich remains on the side of the wall 56 of the connector element 6 thatfaces the filter bowl 8 when it is fully attached to the connectorelement 6. The four pegs 98 are all upstanding from the face of plate 96which faces the first end 42 of the conduit element 38, and are allspaced from the side wall 40 by a sufficient distance that when each peg98 passes through a peg aperture 106 in the wall 56 of the connectorelement 6 the free ends of the pegs 98 abut the face of the plateelement 66. The free ends of the pegs 98 are the ends remote from theplate 96.

The pegs 98 are upstanding from the plate 96 by a distance sufficientthat, when (as illustrated in FIG. 8a ) the conduit element 38 is in theinlet shutoff valve open configuration as a result of the interactionbetween the second end of the conduit element 38 and the base 78 of thefilter bowl 8, the pegs 98 impel the plate element 66 into the outletshutoff valve open configuration and compresses the biasing means 68.

When the second end of the conduit element 38 and the base 78 of thefilter bowl 8 ceases to interact, the biasing means 68 expands andimpels the plate element 66 into the outlet shutoff valve closedconfiguration. At the same time, the plate element 66 bears upon theends of the pegs 98 and impels the conduit element 38 so that the firstend 42 approaches the wall 36 and the inlet shutoff valve moves into theinlet shutoff valve closed configuration (as illustrated in FIG. 8b ).This arrangement is advantageous because the biasing means can thus actdirectly on the outlet shutoff valve and indirectly on the inlet shutoffvalve to close both valves at the same time when the filter bowl 8 isdisconnected from the connector means 6, and the connection of thefilter bowl 8 to the connector means 6 causes the filter bowl to actdirectly on the inlet shutoff valve and indirectly on the outlet shutoffvalve to open both valves at the same time.

The fuel filter 2 further includes a frustoconical valve plug 102 and avalve seat 104 which is configured to form a seal when the valve plug102 engages with the valve seat 104. The valve seat 104 is configuredand dimensioned to reversibly engage with a second end of the filterelement 110. The engagement between the valve seat 104 and the secondend of the filter element 110 is a push fit with the push fit beingsufficiently tight that fuel will not flow through the joint between thefilter element 110 and the valve seat 104.

The valve plug 102 has a plug aperture 116 passing through it with thatplug aperture 116 being co-axial with the axis of the frustoconicalvalve plug 102. The plug aperture 116 is so dimensioned that the conduitelement 38 may slidingly move in an axial direction through the plugaperture 116. There is provided a sliding seal (not shown) such as an oring on the face of the plug aperture 116 facing the conduit element 38so that the plug aperture 116 is sealed against the flow of fuel throughthat aperture.

The valve plug 102 is impelled against the valve seat 104 by the biasingmeans 118. That biasing means 118 is a compression helical spring and itis compressed between the face of the plate 96 facing the second end ofthe conduit element 38 and the valve plug 102. The spring force of thebiasing means 118 is chosen so that a predetermined fuel pressure ininlet filter chamber 92 will overcome that spring force and push thevalve plug 102 away from the valve seat 104. This will let fuel flowfrom inlet filter chamber 92 directly into outlet filter chamber 64.

The spring force of the biasing means 118 is less than the spring forceof the biasing means 68. This is required so that the biasing means 118does not prevent the biasing means 68 impelling the inlet and outletshutoff valves into their closed configurations as the filter bowl isdetached from the connector 6.

The above description is meant to be exemplary only, and one skilled inthe art will recognize that changes may be made to the embodimentsdescribed without departing from the scope of the invention disclosed.Still other modifications which fall within the scope of the presentinvention will be apparent to those skilled in the art, in light of areview of this disclosure.

Various aspects of the fuel filters disclosed in the various embodimentsmay be used alone, in combination, or in a variety of arrangements notspecifically discussed in the embodiments described in the foregoing andthis disclosure is therefore not limited in its application to thedetails and arrangement of components set forth in the foregoingdescription or illustrated in the drawings. For example, aspectsdescribed in one embodiment may be combined in any manner with aspectsdescribed in other embodiments. Although particular embodiments havebeen shown and described, it will be obvious to those skilled in the artthat changes and modifications may be made without departing from thisinvention in its broader aspects. The scope of the following claimsshould not be limited by the embodiments set forth in the examples, butshould be given the broadest reasonable interpretation consistent withthe description as a whole.

1. A fuel filter comprising: a manifold; a connector element; a filterbowl; a filter element; an inlet shutoff valve; an outlet shutoff valve;an inlet port; an inlet passage; an outlet port; an outlet passage; anda relief valve; wherein the connector element is fixed to the manifold,and the filter bowl is reversibly fixed to the connector element;wherein the filter bowl is adapted to reversibly receive the filterelement and is so configured that when the filter element is locatedwithin the filter bowl and the filter bowl attached to the connectionelement the filter element divides the space defined by the connectorelement and filter bowl into an inlet filter chamber and an outletfilter chamber; wherein the inlet port is incorporated in the manifold,and the inlet port and inlet filter chamber are in fluid communicationvia the inlet passage; wherein the outlet port is incorporated in themanifold and the outlet port and outlet filter chamber are in fluidcommunication via the outlet passage; wherein the inlet shutoff valve isbiased by an inlet shutoff valve biasing means into a closedconfiguration which prevents fuel flowing along the inlet passage whenthe filter bowl is not connected to the connection element; whereinconnection of the filter bowl to the connection element causes the inletshutoff valve to be impelled into an open configuration which allowsfuel to flow along the inlet passage; wherein the outlet shutoff valveis biased by an outlet shutoff valve biasing means into a closedconfiguration which prevents fuel flowing along the outlet passage whenthe filter bowl is not connected to the connector element; whereinconnection of the filter bowl to the connector element causes the outletshutoff valve to be impelled into an open configuration which allowsfuel to flow along the outlet passage; wherein the relief valve isbiased by a relief valve biasing means into a closed configuration inwhich fuel flowing between the inlet passage and outlet passage passesthrough the filter element, and movement of the relief valve, into anopen configuration allows fuel to flow between the inlet passage and theoutlet passage via the relief valve without the fuel passing through thefilter element; and wherein the relief valve is caused to move into itsopen configuration when a predetermined fuel pressure is reached withinthe inlet passage and inlet chamber.
 2. The fuel filter according toclaim 1, wherein the impelling of the inlet shutoff valve and the outletshutoff valve into their open configuration commences after commencementof connection of the fuel filter bowl to the connector element andbefore the fuel filter bowl is fully connected to the connector element.3. The fuel filter according to claim 1, wherein: the inlet passagecomprises a second inlet chamber; one or both of the manifold and theconnection means define the second inlet chamber and first and secondinlet chamber apertures, in which the first inlet chamber aperture is amouth of the portion of the inlet passage extending from the fuel inletport, and at least one sliding seal extends around the edge or innerface of the second inlet chamber aperture; the inlet shutoff valvecomprises a longitudinally extending conduit element; the conduitelement is configured to extend through the second inlet chamberaperture in a sliding engagement with the sliding seal means; theconduit element comprises a first closed end, a second end, one or moreside walls, and a stop means; the one or more side walls of the conduitelement extend between the first and second ends; at least one side wallof the conduit element defines at least one first fuel aperture passingthrough the side wall at a position spaced from the first end; the stopelement of the conduit element extends laterally from the first end orfrom one or more side walls adjacent the first end; the stop element ofthe conduit element prevents the first end of the conduit elementpassing through the second inlet chamber aperture; each first fuelaperture of the conduit element is sufficiently longitudinally spacedfrom the first end of the conduit element that when the stop elementabuts the face of the manifold or connection means that defines thesecond inlet chamber aperture each sliding seal means is in contact witha blank portion of the or each side wall; the blank portion of the oreach side wall of the conduit element contains no first fuel aperturesand lies longitudinally between the first end and the or each fuelaperture; the conduit element further comprises one or more second fuelapertures which are defined by one or more of the side walls of theconduit element; and the one or more second fuel apertures of theconduit element are located longitudinally between the one or more firstfuel apertures and the second end of the conduit, and the conduitelement is dimensioned and configured so that when the filter bowl isfully attached to the connector element the second end of the conduitelement abuts a part of the filter bowl, the first fuel apertures mouthinto the second inlet chamber and the second fuel apertures mouth intothe inlet filter chamber.
 4. The fuel filter according to claim 3,further comprising: an intermediate structure, in which the second endof the conduit element abuts a part of the filter bowl via theintermediate structure when the filter bowl is fully attached to theconnector element, and the intermediate structure is configured anddimensioned so that the biasing means may displace the intermediatestructures and move the conduit element into the closed configurationwhen the filter bowl is detached from the connection element .
 5. Thefuel filter according to claim 1, wherein the outlet passage comprises asecond outlet chamber, and one or more outlet intermediate structures;and wherein: one or both of the manifold and the connector elementdefines the second outlet chamber and a first and one or more secondoutlet chamber apertures; the first outlet chamber aperture is a mouthof the portion of the outlet passage extending from the fuel outletport; each second outlet chamber aperture is in fluid communication withthe outlet filter chamber; the outlet shutoff valve comprises anaperture closure element; the aperture closure element is configured tooverlie all of the second outlet chamber apertures; the aperture closureelement is movable between a closed configuration in which the apertureclosure element closes all of the second outlet chamber apertures and anopen configuration spaced from the second outlet chamber apertures; theaperture closure element is biased into the closed configuration by thebiasing means; each outlet intermediate structure is dimensioned andconfigured to contact a portion of the filter bowl when the filter bowlis fully attached to the connector element; the outlet intermediatestructures impel the aperture closure element into its openconfiguration when the filter bowl is attached to the connector element;and the outlet intermediate structures allow the biasing means todisplace those structures and move the aperture closure element into theclosed configuration when the filter bowl is detached from theconnection element.
 6. The fuel filter according to claim 1, wherein oneof the outlet intermediate structures is the conduit element of theinlet shutoff valve.
 7. The fuel filter according to claim 1, wherein atleast one of the inlet and outlet shutoff valve biasing means and therelief valve biasing means is a compression spring.
 8. The fuel filteraccording to claim 1, wherein the inlet and outlet shutoff valve biasingmeans are the same biasing means.
 9. The fuel filter according to claim1, wherein the relief valve comprises a valve seat and a valve plug, therelief valve biasing means biases the valve plug against the valve seat,and the valve plug moves between the open and closed configurations ofthe relief valve.
 10. The fuel filter according to claim 9, wherein thevalve plug has a frustoconical configuration.
 11. The fuel filteraccording to claim 9, wherein the valve seat defines at least part of apassage between the inlet filter chamber and the outlet filter chamberwhere the relief valve is downstream of the inlet shutoff valve andupstream of the outlet shutoff valve.
 12. The fuel filter according toclaim 3, wherein: the relief valve comprises a valve seat and a valveplug, the relief valve biasing means biases the valve plug against thevalve seat, and the valve plug moves between the open and closedconfigurations of the relief valve; and the valve plug defines a plugaperture extending through the plug, the plug aperture has anorientation substantially parallel to the direction of movement of thevalve plug between the open and closed configurations of the reliefvalve, the conduit element of the inlet shutoff valve passes through theplug aperture with a portion of the conduit element between the firstand second fuel apertures of the conduit element in a sliding sealingengagement with the valve plug.
 13. The fuel filter according to claim12, wherein the conduit element of the inlet shutoff valve comprises abiasing means mounting element, and the relief valve biasing meansextends between the valve plug of the relief valve and the biasing meansmounting element of the conduit element.
 14. The fuel filter accordingto claim 13, wherein the relief valve biasing means exerts less springforce than one or both of the inlet shutoff valve and outlet shutoffvalve biasing means.
 15. A method of supplying fuel to a combustor of agas turbine engine comprising: passing the fuel through a fuel filteraccording to claim 1 prior to introduction of the fuel into thecombustor.